The present invention relates to a stent configured for insertion into a lumen or body cavity of a subject.
Conventionally, several types of thermal treatment systems have been proposed to treat certain pathologic conditions of the body by heating or thermally ablating targeted tissue. These thermal treatment systems have used various heating sources to generate the heat necessary to treat or ablate the targeted tissue. For example, laser, microwave, and radio-frequency (RF) energy sources have been proposed to produce the heat which is then directed to the targeted tissue in or around the selected body cavity. Thermal treatment systems have been used to thermally ablate the prostate (as well as other organs, body cavities, and/or natural lumens).
One particularly successful thermal ablation system is directed to thermally ablating the prostate by a thermocoagulation process. This thermal ablation system employs a closed loop liquid or water-induced thermotherapy (WIT) system which heats liquid, typically water, external to the body and then directs the circulating heated water into a treatment catheter which is inserted through the penile meatus and held in position in the subject undergoing treatment to expose localized tissue to ablation temperatures. The treatment catheter includes an upper end portion which, in operation, is anchored against the bladder neck and an inflatable treatment segment which is held relative to the anchored upper end portion such that it resides along the desired treatment region of the prostate. In operation, the treatment segment expands, in response to the captured circulating fluid traveling therethrough, to press against the localized or targeted tissue in the prostate to expose the tissue to increased temperatures associated with the circulating liquid, thereby thermally ablating the tissue at the treatment site. In addition, the pressurized contact can reduce the heat sink effect attributed to blood circulation in the body, thus enhancing the depth penetration of the heat introduced by the inflatable treatment segment into the prostatic tissue.
As an acceptable alternative to surgery (transurethral resection of the prostate (TURP)), the use of WIT (water-induced thermotherapy) has been shown to be particularly suitable for the treatment of BPH (benign prostatic hyperplasia). Generally stated, the term xe2x80x9cBPHxe2x80x9d refers to a condition wherein the prostate gland enlarges and the prostatic tissue increases in density which can, unfortunately, tend to close off the urinary drainage path. This condition typically occurs in men as they age due to the physiological changes of the prostatic tissue (and bladder muscles) over time. To enlarge the opening in the prostatic urethra (without requiring surgical incision and removal of tissue), the circulating hot water is directed through the treatment catheter, which is inserted into the penile meatus up through the penile urethra and into the prostate as described above. The treatment segment expands with the hot water held therein to press the inflated treatment segment against the prostate, which then conductively heats and thermally ablates the prostatic tissue. The circulating water is typically heated to a temperature of about 60-62xc2x0 C. and the targeted tissue is thermally treated for a period of about 45 minutes to locally kill the tissue proximate the urinary drainage passage in the prostate and thereby enlarge the urinary passage through the prostate.
Subsequent to the delivery of the thermal ablation treatment, the treated tissue in the prostate undergoes a healing process. Initially, the ablated tissue can expand or swell due to inflammation or edema which can undesirably block or obstruct the prostatic urethra. Further, during the healing period, portions of the treated tissue can slough off and create an undesirable and unduly limited opening size. This post-ablation treatment opening size can be positively influenced by xe2x80x9cmoldingxe2x80x9d the ablated tissue during the healing cycle to contour the tissue about a catheter or stent held thereat. Therefore, to facilitate proper healing and to enhance the efficacy of the ablation therapy, either the treatment catheter is left in the subject for a period of time and/or a post treatment catheter, such as a conventional Foley catheter, is positioned in the subject. However, the amount of time that the treatment or post-treatment catheter must reside in the subject can be from 2-14 days, or even longer. Therefore, it is desirable to configure the post-treatment catheter in a minimally invasive manner to allow normal operation of the sphincter, remove the need for the use of an incontinence bag, and reduce the inconvenience or discomfort to the user.
Conventionally, Foley-type catheters with bladder anchoring balloons located on an upper end portion have been used as post-treatment catheters to allow the thermally ablated tissue to mold around the catheter perimeter during the initial healing phase. While these type catheters allow the post-treatment catheter to be securely positioned relative to the bladder neck of the subject, natural operation of the sphincter is inhibited, and the configuration is relatively cumbersome (in position it extends through the penile urethra) and can be considered unduly invasive by the user and may increase the risk of urinary tract infection (UTI) when in position in the subject (particularly, when used for extended periods of time). Other post-treatment catheter configurations (also known as xe2x80x9cindwelling cathetersxe2x80x9d and xe2x80x9cstentsxe2x80x9d) have also been proposed; however, some of the catheter types can inhibit the ability to flush out blood clots which may exist from the therapy, and others are undesirably invasive to the user and/or prevent or inhibit the natural operation of the sphincter. Still others are not able to be properly located within the prostatic cavity about the treatment region and/or are unable to retain their desired position in the prostate over time. Still others can, during prolonged use, promote muscle atrophy and/or localized tissue necrosis.
Examples of known post-treatment catheters or stents are described in U.S. Pat. No. 5,916,195 to Eshel et al., U.S. Pat. Nos. 5,876,417 and 5,766,209 to Devonec et al., and U.S. Pat. No. 3,811,450 to Lord. However, there remains a need to provide improved and/or minimally invasive post-treatment catheters or stents which are cost effective and can be positioned and located in the prostate proximate the treated tissue during the post thermal ablation process or healing cycle (which can contour or mold the tissue) and which can be easily removed at the appropriate time.
It is therefore an object of the present invention to provide a stent which is suitable for inhibiting post thermal ablation obstruction in the prostate and which is configured in a minimally invasive manner to the wearer.
It is another object of the present invention to provide a stent which can be inserted through the penile meatus and penile urethra to be positioned in the prostatic urethra and held in a desired position relative to the thermally treated tissue during prolonged use.
It is yet another object of the present invention to provide a stent which can be locally anchored in a relatively stable manner in the prostate such that longitudinal migration or movement toward or away from the bladder is inhibited.
It is another object of the present invention to provide a device which can inhibit obstruction in the prostatic urethra to keep the urinary drainage path open such that the subject is able to discharge urine in a normal manner.
It is an additional object of the present invention to provide a way to monitor the movement of catheters and/or to provide improved ways to determine that the integrity of the inflation system is intact.
It is another object of the present invention to provide improved stents which are able to inhibit obstruction in a lumen or cavity.
These and other objects are satisfied by the present invention which provides, inter alia, minimally invasive unitary body stents having a length of elongated small tubing which extends therefrom. The length of the small tubing or conduit is sufficient such that it can extend from the unitary body and along the penile urethra to a position outside the body. The stents are configured to reside above the sphincter such that they are held in the prostate during a healing period. Similarly, the present invention includes methods of treating BPH (and other prostate conditions) to inhibit obstruction in the prostatic urethra during a healing period after a thermal ablation treatment therapy.
More particularly, a first aspect of the present invention is a prostatic stent configured for insertion into the male urethra of a subject. The male urethra generally includes, in serial order from the externalmost portion to the internal portion, the penile meatus, the penile urethra, the bulbous urethra, the sphincter, the membranous urethra, the prostatic urethra, the bladder neck and the bladder. The prostatic stent includes a unitary tubular body having a central lumen extending therethrough and a first cross-sectional width thereacross. The stent also includes a tissue-engaging inflatable balloon positioned on a lower perimeter portion of the unitary body and at least one conduit having opposing upper and lower end portions with a fluid lumen formed therein. A portion of the upper end of the conduit is attached to the unitary tubular body such that it is in fluid communication with the inflatable balloon. The conduit has a second cross-sectional width which is less (preferably substantially less) than the first cross-sectional width of the unitary tubular body. In position in the subject, the stent is configured such that the unitary body resides above the sphincter and the conduit extends through the sphincter and out of the penile meatus of the subject. In addition, the conduit is configured in size and/or cross section such that it allows substantially natural closing of the sphincter when the stent is in position in the subject.
Another aspect of the present invention is a set of prostatic stents, each configured for insertion into the male urethra of a subject as stated above. However, the set is provided such that each unitary body is sized a different length to allow customized fit to a particular subject (the portion of the stent body which is adapted to reside in the membranous and prostatic urethra itself and typically ranges in length from about 4-10 cm).
Yet another aspect of the present invention is a method of treating BPH. The method includes the steps of (a) thermally ablating a localized treatment region in the prostatic urethra of a subject such that the urethra below the prostatic urethra, about or proximate the membranous urethra, remains substantially non-ablated; (b) inserting a stent into the prostate of the subject after the thermally ablating step, the stent having a unitary body, a lower inflatable portion formed thereon, and a conduit extending downwardly therefrom; (c) positioning the stent in the subject such that the unitary body resides above the sphincter and the conduit extends downwardly therefrom through the sphincter and out of the penile meatus, wherein the conduit is sized to allow the sphincter to function substantially normally with the stent in position in the body; (d) inflating the lower inflatable portion after the inserting step such that the lower inflatable portion engages with tissue which is located below the treatment region and a portion of the stent resides proximate the treatment region and above the sphincter; (e) inhibiting the obstruction or closure of the prostatic urethra during a healing period subsequent to said thermal ablating step; (f) deflating the lower inflatable portion; (g) and removing the stent after the deflating step and after a period of about two to fourteen days from the time of initial insertion of the stent.
In certain embodiments, the stent is removed by deflating the lower inflatable portion and then pulling the conduit to force the stent from the subject. The inserting step may be carried out after an initial healing period of about 12-72 hours (typically when a treatment catheter is left in the body), and preferably, about 24-48 hours, from the end of the thermal ablation therapy to avoid unnecessary contact or manipulation of the treatment site to inhibit bleeding of the treated tissue. Inserting the stent after an initial healing period can reduce bleeding which may occur upon premature removal of the treatment catheter after delivery of the active thermal ablation treatment.
Another aspect of the present invention is a method of inhibiting the obstruction of the prostatic urethra in a minimally invasive manner, comprising the step of inserting a stent, having a unitary body and a length of at least one conduit attached thereto, into the penile meatus of a subject and along the penile urethra until the stent is located in a desired location in the prostatic urethra such that the stent unitary body resides above the sphincter and the conduit extends through the spinchter and out of the penile meatus, wherein the conduit is sized to allow the sphincter to close in a substantially natural manner when the stent is in position in the subject.
The at least one conduit can be two (or more) conduits: a first conduit in fluid communication with a bladder anchoring balloon, and a second conduit in fluid communication with a lower inflatable portion. In addition, the first conduit can be releasably attached to the stent. In one embodiment, one conduit can be detached from the stent while the stent is in situ (in the subject) after the step of positioning the stent into the subject""s prostate, when the detachable conduits in fluid communication with the anchoring balloon inflated after the positioning step.
In other embodiments, the conduit can include externally visible indicia of movement positioned along an externally disposed portion of the conduit (when the stent is in the subject). The method can, thus, include the step of monitoring the movement of the stent in the subject corresponding to the change in position of the external indicia. In addition externally visible indicia of the integrity of, or proper degree of inflation of, the inflation balloons in the body (whether localized or bladder anchoring balloons) can be operably associated with the conduit(s). The stent can also be configured with radiopaque markers to allow for positional verification of the stent (such as by X-ray) when in the body. In addition, the external surface of the stent, particularly the unitary body and inflation portions, can include surface treatments such as anti-microbial and/or anti-frictional coatings.
Yet another aspect of the present invention is a further method of treating BPH. The method comprises the steps of (a) inserting a treatment catheter configured to circulate heated liquid along the penile urethra to the prostate of a subject; (b) circulating liquid heated to above about 45xc2x0 C. in the treatment catheter; (c) directing the circulating heated liquid of the circulating step such that it travels, captured in the treatment catheter, to a localized treatment region in the prostate; (d) exposing targeted tissue in the prostate in a localized treatment region to a temperature of above about 45xc2x0 C. for a predetermined thermal ablation treatment period corresponding to liquid provided by the circulating and directing steps; (e) terminating the circulation of the heated liquid after the thermal ablation treatment period; (f) leaving the treatment catheter in the subject after the terminating step for an initial healing period of from about 12-72 hours; (g) removing the treatment catheter after the initial healing period; (h) inserting a post-treatment stent having a unitary body and at least one conduit extending therefrom into the subject after the removing step; (i) positioning the post-treatment stent with a unitary body and a elongated conduit extending therefrom in the subject such that the unitary body resides above the sphincter and the conduit extends through the sphincter, the penile urethra, and the penile meatus such that a lower portion resides outside the subject, and such that a portion of the stent resides in the localized treatment region of the prostate to allow the tissue to mold thereabout during a post thermal ablation healing period, wherein the post-treatment stent comprises a lower inflatable portion; (j) expanding the lower inflatable segment such that it engages with tissue below the localized treatment region and above the sphincter; and (k) removing the stent from the subject, after deflating the lower inflatable segment, by pulling on the conduit located outside the subject to dislodge and slide the stent along the penile urethra to free the stent after a healing period of about 2-14 days thereby inhibiting the obstruction of the prostatic urethra by allowing the tissue to mold or migrate about the perimeter of the stent as it heals to facilitate a desired prostatic urethra opening thereabout.
In a preferred embodiment, the conduit includes graduation marks on the portion which is adapted to be external of the subject when the stent is in position in the subject, and the method further comprises the step of monitoring the movement of the stent in the body corresponding to the travel of the graduation marks toward or away from the penile meatus. In another embodiment, the at least one conduit comprises two conduits both attached to the unitary body of the stent, and the method further comprises the steps of detaching a selected one of the conduits in situ from the stent body and removing it from the subject when the stent is in use (and in position in the body). As noted above, the stent can also include externally visible movement indicia and inflation indicia.
Advantageously, the present invention provides post-treatment stents or stents which can be used to inhibit prostate obstruction in the urinary drainage path in a minimally invasive manner. The unitary body stent is configured to reside in the subject above the sphincter with only one or more conduits extending therefrom and out of the body of the subject. The stent can include one or more of a lower tissue engaging anchoring balloon, an upper bladder neck anchoring balloon, and an expandable tissue molding intermediate section. The conduits can be configured to direct an inflation medium to and from the desired inflation region in the stent. One or more of the conduits can be releasably attached to the stent such that it is detachable in situ. The detachable conduit can be externally visually marked or configured such that it is readily identifiable during operational use by a clinician.
The conduit can also include external indicia of movement (and/or a xe2x80x9cstopxe2x80x9d), such as graduation marks to allow a user or clinician to monitor the movement of the catheter toward or away from the penile meatus or other landmark to identify when or if the stent has dislodged from its desired location in the subject.
The unitary body stent is configured to allow drainage and/or flushing liquids to be directed into the subject therethrough, and is particularly suitable for chronic wearing (such as 2-14 days) by a user undergoing a healing period after a thermal ablation therapy has been applied to a localized region of the prostate. The instant invention is also particularly suitable for insertion after an initial healing period to reduce irritation introduced to the ablated tissue (which can reduce the number of blood clots produced by the subject). The stent can include one or more conduits, one of which can be used to deliver medicaments or saline rinses to the treatment region during the healing process (to promote healing and/or inhibit UTI). The stent can be positioned in the body by attachment to a pusher which is configured to securely hold the stent thereagainst by inflation of one or more attachment balloons.